Duplicating sheet and colored coating compositions therefor



3,096,189 Patented July 2, 1963 3 096,189 DUPLICATING SHEET AND COLOREDCOATING COMPOSITIONS THEREFOR Frederick H. Kranz and Floyd L. Tewksbury, In, Buffalo, N.Y., assignors to Allied Chemical Computation,New York, N.Y., a corporation of New York No Drawing. Filed Dec. 10,1958, Ser. N0. 779,276 14 Claims. (Cl. 106-236) This invention relatesto a duplicating sheet and to colored coating compositions therefor. Itrelates more particularly to duplicating sheets of the so-calledsinglecopy carbon paper type; that is, duplicating sheets which are usedonly once and then discarded; and to coating compositions for thepreparation thereof.

Duplicating sheets of the type under consideration usually consist of asheet of paper coated on one side with a colored film which is adaptedto be transferred to a receiving sheet by the application of pressure tothe surface of the duplicating sheet, as by a stylus, typewriter, etc.

Primary requirements of duplicating sheets, especially of thesingle-copy" carbon paper type, are that both the coated surface of theduplicating sheet and copy inscriptions transferred to a receiving sheetpossess good resistance to smudging, soiling, offset and color runduring ordinary handling and use. These properties, which, of course,are highly desirable in all types of duplicating paper, are criticallyimportant in duplicating papers used to transfer inscriptions to cardswhich are to be processed by certain modern automatic machines whichfunction responsive to information retrieved from the cards, such as,automatic scanning and sorting machines, and punch-card machines. Cardsof this type may, for example, contain a copy inscription from a salesslip representing credit purchases at a gasoline filling station inwhich part of the inscribed copy is obtained from a credit card stampingplate. Such copies should have inscriptions of good color and should befree of color smudgcs and smears, which interfere with the properfunctioning of such machinery. Cards containing copy inscriptionsobtained by means of ordinary duplicating papers heretofore availablehave proved highly unsatisfactory, because color runs and offsets of Waxand color on such cards have interfered with the operation of themachines.

It has been proposed in U.S. Patent 2,299,694 to overcome thisdifiiculty by providing a duplicating sheet consisting of a base sheetcoated with a pressure-rupturable coating formed of a plastic solidhydrophobic gum as continuous phase having dispersed therein discretecolored droplets consisting of a suspension of carbon black in apolyhydric alcohol or a solution of Malachite Green dye in glycerine.Owing to the fact that Malachite Green is a water-soluble dye, thecharacters obtained with it on a copy sheet are subject to smearing,offsetting and running when handled in moist weather or with damp hands.

We have discovered that improved duplicating sheets of the above typeand coating compositions for the production thereof can be obtained byemploying, as the colored liquid dispersed as droplets (thediscontinuous phase) in a plastic solid hydrophobic material (ascontinuous phase), a solution of one or more of a particular class ofwater-insoluble colorants in one or more of a particular class ofhydrophilic oxygen-containing organic liquids which are solvents forsaid colorants. Thus, we have discovered that such solutions can bereadily dispersed into the hydrophobic material to form coatinigcompositions which, when applied as a film to a base sheet material bythe usual procedures (e.g., hot-melt coating or solvent coating), resultin duplicating sheets having a number of desirable properties; they donot smudge or cause discoloration when handled in a humid atmosphere orwith damp fingers, and when used in copying by the application ofpressure of a stylus, typewriter key or raised plate to the duplicatingsheet, the film of coating is ruptured and the droplets of coloredsolution are released and are absorbed by the receiving sheet, leavingmarkings of the colorant on the receiving sheet. Since the colorant isinsoluble in water the markings do not smudge, smear, run, or off-setwhen handled in a moist atmosphere or with damp hands or even whensubjected to water, as in the rain; and, in view of the high degree ofsolubility of the colorants in the hydrophilic solvents, the markingsare of good color strength, legibility and definition. Since, unlikeordinary carbon paper, the continuous phase of the coating is not itselfthe color carrying vehicle, relatively harder plastic solid hydrophobicmaterials can be employed as the continuous phase of the coating; sothat greater smudge resistance is obtained and only innocuous amounts ofwax or other hydrophobic material are transferred to the receivingsheet.

The colorants employed in accordance with the present invention arewater-insoluble salts of organic bases (and especially organic dyestufibases) with organic dyestuff sulfonic acids, and especially those inwhich at least one of the base and acid components is of thetriphenylmethane class. Those which contain a triphenylmethane dye as atleast one component of the molecule are preferred because of their highcolor value.

The colorants can be prepared by heating a mixture of an aqueoussolution of the organic base with an aqueous solution of the dyestufisulfonic acid. The resulting sulf-onate salt of the organic base, beinginsoluble in water, precipitates out and is isolated, dried and ground.

Suitable organic bases include basic dyestuffs of the triphenyhnethane,Xanthene, azine and azomethine classes; and organic amines (includingamidines) containing more than 10 carbon atoms in the molecule, such asdialkylamines, trialklarnines and diarylguanidincs (es pecially of thebenzene series, like diphenyl-, ditolyland dixylylguanidines), which arewithout color value but which impart the requisite solubilitycharacteristics to the molecule.

Suitable dyestutf sulfonic acids include triphenylmethane, azo,xanthene, azomethine, anthraquinone, dioxazine, phthalocyaninc and otherdyes which contain at least 1, and preferably more than 1, sulfonic acidgroup, or groups which react as sulfonic acid groups (i.e. sodiumsulfonate groups or sulfonate groups internally linked by an ionic bondto a quaternary nitrogen atom in a dyestuif molecule).

Colorants of this type are illustrated by the following, in which thenumber of 111015 of basic component is equivalent to the number ofsulfonic acid groups present in the dyestuff sulfonic acid. The CI.designations refer to Colour Index numbers given in Colour Index, SecondEdition (1956).

Dixylylguanidine salt of Wool Violet 4BN (CI. 42640) Dixylylguanidinesalt of Brilliant W001 Blue FFR Extra Ditolylguanidine salt of Fast WoolBlue R (0.1. 13390) Salt of Rhodamine 6GDN (CI. 45160) with ChromolanYellow N (CI. 19010) Ditolylguanidine salt of Sirius Light Blue FFRL(prepared as described in BIOS Final Report No. 760, pp. 77-8)Dixylylguanidine salt of Brilliant Acid Blue 6BN (C.I.

Salt of Crystal Violet (Cl. 42555B) with Alphazurine FG (C.I. 42090) 3Salt of Crystal Violet with Buffalo Black NBR (CI.

20470) Salt of Crystal Violet with Light Green SF Yellowish (Cl. 42095)Salt of Rhodamine B Base (C.I. 45170B) with Crocein Scarlet SS (C.I.27290) The hydrophilic oxygen-containing organic liquids employed inaccordance with the present invention are liquids which, besides beinghydrophilic and oxygen-containing, have good solvency for the colorants(they dissolve at least and preferably at least 35% by weight of theselected colorant) and are immiscible with the normally solid plastichydrophobic material employed as continuous phase of the duplicatingsheet coating. Particularly suitable hydrophilic oxygen-containingliquids are characterized by the following properties:

They are liquid at ordinary atmospheric temperatures, preferably attemperatures at least as low as C. and especially as low as 30 C.

They have a high boiling point, preferably above 150 C.

They have a low vapor pressure, preferably below 0.1 mm. of mercury at25 C.

They have a high flash point, preferably above 100 C.

They have a molecular weight above 60.

They contain more than 10% by Weight of oxgen in the molecule.

The following are illustrative of hydrophilic oxygencontaining organicliquids suitable for use in accordance with the present invention:

Glycols, such as ethylene glycol, propylene glycol, hexylene glycol,octylene glycol, etc.

Other polyhydric alcohols, such as butanediol-l,3; pentanediol-l,5;glycerol; etc.

Polyalkylene glycols and their corresponding thioethers, such as,diethylene glycol, triethylene glycol, higher polyethylene glycols,dipropylene glycol, tripropylene glycol, higher polypropylene glycols,thiodiethylene glycol, etc.

Glycol ethers, such as, alkyl ethers of the above; e.g., monoethyl etherof diethylene glycol (Carbitol) or of triethylene glycol, dimethyl etherof tetraethylene glycol, etc.

Hydroxyalkyl amines, such as, ethanolamine.

Organic carbonates, such as, ethylene carbonate and propylene carbonate.

Ketones, such as, cyclohexanone.

Those of the above hydrophilic oxygen-containing liquids, or mixturesthereof, which have the formula R'O( R0 H wherein R represents a memberof the group consisting of H and C -C alkyl groups,

R is an alkylene group containing from 2 to 10 carbon atoms, inclusive,

n is an integer from 1 to 12, inclusive, and

the total number of carbon atoms is from 2 to 24, in-

elusive,

and especially those (jg-C24 compounds in which R in the above formularepresents a C -C alkylene group, are preferred for use as solvents forthe Water-insoluble colorants. Those of the latter class of solvents inwhich R in the above formula represents hydrogen, and especiallymixtures of polyethylene glyeols having average molecular weights of 200to 500, are of particular utility in accordance with the presentinvention.

Various plastic solid hydrophobic materials which are immiscible withthe hydrophilic oxygen-containing liquids employed can be used as thecontinuous phase of the pressure-rupturable coating, a number of whichare known. They include normally solid materials which are capable ofbeing melted without decomposition at moderately elevated temperatures(e.g. below 150 C.), so that they may be applied by hot-melt coatingmethod; and/or which are soluble in volatile hydrophobic solvents(especially hydrocarbons, such as, toluene, coal tar naphtha, or variouslow boiling solvent-grade petroleum distillates so that they may beapplied by solvent-coating methods with subsequent removal of thesolvent by evaporation; and mixtures thereof. Thus, they include waxesand resins and mixtures thereof.

The following are illustrative of suitable waxes: montan wax, carnaubawax, ouricoury wax, esparto wax, ceresin, ozokerite, beeswax, sugar canewax, paraffin Wax, microcrystalline or petrolatum wax, and waxy amidesof longchain fatty acids.

The following are illustrative of suitable resins: polyethylene,polyisobutylene, other polymerized hydrocarbon resins such as may beobtained by treatment of unsaturated hydrocarbon distillates withFriedel-Crafts catalysts, and hydrocarbon-soluble alcohol-insolublenatural resins (such as, gum damrnar).

Plasticizing agents, such as light or heavy mineral oil, petrolatum,lard oil, or dioctyl phthalate may be incorporated with the waxes and/or resins if desired.

The coating compositions are prepared by dispersing a solution of thewater-insoluble colorant or mixture of such colorants, in thehydrophilic oxygen-containing organic liquid, or mixture of such liquids(preferably a solution containing a high concentration of colorant), inthe hydrophobic material in liquid form (in molten form or in solutionform). Dispersing is preferably effected by mixing the said componentsin efficient, high-speed mechanical dispersion equipment, such as a KadyMill or Waring Blender. Chemical emulsifying agents may be used ifdesired but are generally not necessary. The amount of color solutionmay range from 20% to 80% of the weight of the total formulation(exclusive of volatile solvent, where used), depending, among otherthings, on the color strength of the solution. Mixing is continued untilthe desired degree of dispersion is obtained. The size of the disperseddroplets may range from 0.1 to microns. Average sizes of droplets in therange 0.5 to 20 microns, and more particularly in the range 1 to 5microns, are preferred.

Coating compositions of exceptionally high quality may be made byencapsulating the colored solution in a resin (cg. gum dammar) to formbead-like capsules which are then dispersed in the continuous phase ofhydrophobic material. For example, a solution of a colorant in a suitable solvent (such as a mixture of polyethylene glycols having anaverage molecular Weight of about 400) may be dispersed in a toluenesolution of a suitable resin (such as one of those referred to above);the resulting dispersion may be spray-dried, during which the tolueneevaporates and the residual material is obtained in the form ofmicrospherical beads containing droplets of colored solutionencapsulated in a shell of resin; and the beads may then be dispersedinto a suitable continuous filmforming hydrophobic material bymechanical mixing.

The coating compositions may be applied in the molten or solution formto the base sheet material in various ways, as is known; for example, bydrawdown blades. or by conventional coating machinery of the direct orreverse roll type, or by printing by direct or olf-set gravure. Hot meltcoatings may be cooled, suitably by air chilling or by passing overchilled rollers. If the coatings as applied contain a volatile solvent,the latter, of course, is removed by evaporation. The weight of coatingapplied may range from 1 to 6 lbs. (preferably about 3 lbs.) per 500sheets of 20" x 30" paper.

The invention will be illustrated by the following specific examples,but it is to be understood that it is not limited to the details thereofand that changes may be made without departing from the scone of theinvention. The temperatures are in degrees centigrade and the parts andpercentages are by weight, unless designated as parts by volume. Whereparts are by volume, the amount signifies the volume occupied by thesame number of parts by weight of water at 4 C.

EXAMPLE 1 This example describes the preparation of a duplicating paperconsisting of a film of a montan wax composition coated on a paper base.The wax composition consists of a. dispersion of discrete minutedroplets of colored monoethylether of diethyleneglycol (Carbitol) asdiscontinuous phase in montan wax as the continuous phase. The Carbitolis colored by having dissolved therein a blue organic colorant which isa wateninsoluble salt of 3 mols of Crystal Violet Base (Solvent Violet9-C.I. 42555B) with l rnol of Alphazurine FG (Acid Blue 9-C.I. 42090).

Part A.-Preparatin of Colorrmt A hot (about 80) solution of 240 parts ofAlphazurine FG (100% strength basis=3 mols) in about 1500 parts of wateris added dropwise to a well stirred hot (80) solution of Crystal Violet(371 parts=1 mol) in about 2,000 parts of water and stirring iscontinued for an additional hour at 80. The resulting mixture is allowedto stand, and the product, which separates out as a tarry mass, ispermitted to settle. The upper layer of water is syphoned off. Theremaining tarry product is purified by adding hot water, stirring theresulting mixture, and then allowing it to cool and settle. Aftersyphoning off the upper aqueous layer, the product is dried under vacuumat 4045. A dry friable solid is obtained which is then ground to apowder in a Mikrolulverizer.

The resulting product is a blue colorant which is substantiallyinsoluble in cold water, but very soluble in oxygenated organicsolvents, as evidenced by the following Table 1, showing in roundnumbers the solubility in representative solvents of this class at roomtemperature.

Part B.--Prepamti0n of Coated Duplicating Sheet A coating composition isprepared by agitating a mixture of the following ingredients at 90 in ahigh speed mixer of the Waring Blender type:

Parts Carbitol 75 Montan wax (16B grade) 200 Blue colorant prepared inPart A During this operation the colorant dissolves in the Carbitol andthe resulting colored Carbitol solution is disersed as minute discretedroplets, constituting the discontinuous phase, of an emulsion of thecolored solution in the molten wax as continuous phase. Upon cooling toroom temperature, the resulting dispersion sets to a plastic solid. Thedispersion is then coated on paper by means of a drawdown plate or othersuitable coating means. The weight of the coating is equivalent to 3pounds per 500 sheets of 20" x paper.

The coated paper is characterized by stability to handling and theexcellence of the copy matter obtained by its use. Thus, the coatedpaper has a high degree of resistance to smudging, soiling, andoil-setting and bleeding of color during normal handling and use. Copyinscriptions transferred to a receiving sheet by means of this coatedpaper are characterized by good definition and legibility, and by a highdegree of freedom from smudging and from smearing of the color and/orwax. As a result, copy inscriptions obtained by the use of the coatedpaper are well adapted for use in connection with auto matic dataprocessing machines, such as, punchcard machines and other types ofautomatic business machines.

EXAMPLE 2 This example describes the preparation of a duplicating paperconsisting of a film of a carnauba wax composition coated on a paperbase. The wax composition consists of a dispersion of discrete minutedroplets of colored monoethylether of diethylencglycol (Carbitol) asdiscontinuous phase in carnauba wax as the continuous phase. TheCarbitol is colored by having dissolved therein a black organic colorantwhich is a water-insoluble salt of 2 mols of Crystal Violet Base(Solvent Violet 9C.I. 42555B) and 1 mol of the base of the orangeazomethine dyestufi having the following formula (see Example 6 of U.S.Patent 2,140,248):

with 1 mol of Light Green SF Yellowish (Acid Green 5C.I. 42095).

Part A.Preparati0n of Colorant A hot (about solution of 198 partsstrength basis=1 mol) of Light Green SF Yellowish in 420 parts of wateris added dropwise to a well stirred hot (80") solution of 205 parts(100% strength basis=2 mols) of Crystal Violet and 106 parts (100%strength basis=1 mol) of the orange azomethine dyestuti having the aboveformula in 1000 parts of water and stirring is continued for anadditional hour at 80. The resulting slurry is allowed to cool. Theproduct precipitates out as a tar. Supernatant water is decanted otf,and the product is reslurried in 2000 parts of hot (80) water. Uponcooling without agitation, the colorant separates out as a tar, which isisolated and dried under vacuum at 4045 and ground to a powder in aMikro-Pulvizer.

The product is a black colorant which is insoluble in cold water but isvery soluble in oxygenated organic solvents such as those set out inTable 1, above.

Part B.-Preparati0n of Coated Duplicating Sheet A coating composition isprepared by agitating a mixture of the following ingredients at 90 in ahigh speed mixer of the Waring Blender" type:

During this operation the colorant dissolves in the Carbitol and theresulting colored solution is dispersed as minute discrete droplets,constituting the discontinuous phase, of an emulsion of the coloredsolution in the molten wax as continuous phase. Upon cooling to roomtemperature, the resulting dispersion sets to a plastic solid. Thedispersion is coated on paper, excess being removed by a doctor bar atto give a coating weight of 3 pounds per 500 sheet 20" x 30" ream.

The coated paper is characterized by exceptional resistance to smudgingor soiling during normal handling and use. Copy inscriptions transferredto a receiving sheet by means of this coated paper are characterized bya strong black color, good definition, good legibility, and exceptionalresistance to smudging and to running of the color in the presence ofmoisture.

EXAMPLE 3 This example describes the preparation of a duplicating paperconsisting of a film of a guru damrnar composition coated on a paperbase. The gum damrnar composition consists of a dispersion of discreteminute droplets of colored polyethylene glycol as discontinuous phase ingum dammar as the continuous phase. It is prepared by dispersing apolyethylene glycol solution of the colorant into a toluene solution ofgum dammar, coating the resulting dispersion on a paper base sheet, andthen evaporating the toluene from the coated surface. The colorant is abluish red water-insoluble salt of 2 mols of Rhodamine B Base (SolventRed 49--C.I. 45170B) with 1 mol of Crocein Scarlet SS (Acid Red 73C.I.27290).

Part A.-Preparation of Column! A bluish red solid is prepared byprecipitation, in the manner described in Examples 1 and 2, Parts Aabove, from hot aqueous solutions of 2 mols of Rhodamine B (Basic VioletlC.I. 45170) and 1 mol of Crocein Scarlet SS, respectively.

The colorant is insoluble in water, but very soluble inoxygen-containing organic solvents. Thus, it has a solubility of about50% in Carbitol and in propylene glycol.

Part B.Preparati0n of Coated Duplicating Sheet A colored polyethyleneglycol solution is prepared by dissolving 6 parts of the colorantobtained in Part A of this example in 24 parts of Polyethylene Glycol400 having an average molecular weight range of 380-420 (a product ofCarbide and Carbon Chemical Co.)

A gum dammar solution is prepared by dissolving 40 parts of gum dammarin 60 parts of toluene.

The colored polyethylene glycol solution is dispersed into the gumdammar solution by agitating them together in a high speed mixer (WaringBlendor), the resulting emulsion is coated on a paper base sheet, andthe toluene is removed from the coating by evaporation.

The resulting coated sheet is resistant to smudging, and gives welldefined, bluish red copy inscriptions which are fast to light and towater.

It will be evident that the invention is not limited to the details ofthe foregoing illustrative examples and that changes can be made withoutdeparting from the scope of the invention.

Thus, instead of the wax and gum employed in the above specificexamples, any of the other plastic solid hydrophobic materials referredto above may be employed as continuous phase and may be applied to thebase sheet by the hot melt or solvent coating procedures.

Instead of the hydrophilic oxygen-containing organic liquids employed inthe above examples, others of the said class of solvents for thecolorants may be substituted for the glycol ether and polyethyleneglycol employed in the above examples.

Similarly, the Water-insoluble organic base salts of organic dyestuifsulfonic acids employed in the specific examples may be replaced byother water-insoluble salts of organic bases with organic dyestuffsulfonic acids.

Since changes may be made in the duplicating sheets and compositions forpreparing them without departing from the scope of the invention, it isintended that all matter contained in the above description shall beinterpreted as illustrative and not in a limiting sense, except aslimited by the claims.

We claim:

1. A duplicating sheet in the form of a base sheet and apressure-rupturable coating on said sheet consisting essentially of aplastic solid hydrophobic material selected from the group consisting ofwaxes, resins, and mixtures thereof as continuous phase discrete coloreddroplets dispersed therein as discontinuous phase, thereby characterizedthat said colored droplets consist essentially of a solution of awater-insoluble colorant which is at least one salt of an organic basewith an organic dyestufi sulfonic acid in a hydrophilic oxygencontaining organic liquid solvent for said salt which is immiscible withsaid hydrophobic material.

2. A duplicating sheet as defined in claim 1 in which the hydrophilicoxygen-containing organic liquid is liquid at temperatures at least aslow as 10 C. and has a boiling point above 150 C., a vapor pressurebelow 0.1 mm. of mercury at 25 C., a flash point above C., and amolecular weight above 60, and contains more than 10% by weight ofoxygen in the molecule.

3. A duplicating sheet as defined in claim 1 in which the hydrophilicoxygen-containing organic liquid is at least one compound of the formulaR'O(RO) H wherein R represents a member of the group consisting of H andC -C alkyl groups,

R is an alkylene group containing from 2 to 10 carbon atoms, inclusive,

n is an integer from I to 12, inclusive, and

the total number of carbon atoms is from 2 to 24 inclusive.

4. A duplicating sheet as defined in claim 3 in which the hydrophilicoxygen-containing organic liquid is at least one C -C compound havingthe formula R'O (RO),,H wherein R represents a member of the groupconsisting of H and C1-C8 alkyl,

R represents C 0 alkylene, and

n represents an integer from 1 to 12, inclusive.

5. A duplicating sheet as defined in claim 3 in which the hydrophilicoxygen-containing organic liquid is an open-chain organic dihydroxycompound having the formula HO (RO),,H wherein R represents C -Calkylene, and n equals 1 to 12, inclusive.

6. A duplicating sheet as defined in claim 1 in which theWater-insoluble colorant is a salt of an organic dyestuff base with anorganic dyestuff sulfonic acid, and the hydrophilic oxygen-containingorganic liquid is a mixture of polyethylene glycols having an averagemolecular weight of 200 to 500.

7. A duplicating sheet as defined in claim 6 in which thewater-insoluble colorant is a salt of an organic dyestuff base with anorganic dyestuff sulfonic acid, at least one of which is of thetriphenylmethane class.

8. A duplicating sheet as defined in claim 6 in which thewater-insoluble colorant is a salt of a triphenylmethane dyestutf basewith an organic dyestutf sulfonic acid.

9. A coating composition for the production of a duplicating sheetconsisting essentially of a dispersion of discrete colored droplets asdiscontinuous phase in a plastic normally solid hydrophobic materialselected from the group consisting of waxes, resins and mixtures thereofas continuous phase, thereby characterized that said colored dropletsconsist essentially of a solution of a water-insoluble colorant which isat least one salt of an organic base with an organic dyestufi sulfonicacid in a hydrophilic oxygen-containing organic liquid solvent for saidsalt which is immiscible with said hydrophobic material.

10. A coating composition as defined in claim 9 in which the hydrophilicoxygen-containing organic liquid is liquid at temperatures at least aslow as 10 C. and has a boiling point above C., a vapor pressure below0.1 mm. of mercury at 25 C., a flash point above 100 C., and a molecularweight above 60, and contains more than 10% by weight of oxygen in themolecule.

11. A coating composition as defined in claim 10 in which thewater-insoluble colorant is a salt of an organic dyestulf base with anorganic dyestuff sulfonic acid, at least one of which is of thetriphenylmethane class.

12. A coating composition as defined in claim 10 in which thewater-insoluble colorant is a salt of a triphenylmethane dyestuff basewith an organic dyestufi sulfonic acid.

13. A coating composition as defined in claim 10 in which the normallysolid hydrophobic material is a wax melting below 150 C.

14. A coating composition for the production of a duplicating sheetconsisting essentially of an emulsion of discrete colored dropletsdispersed as discontinuous phase in a solution in a hydrocarbon solventof a normally solid plastic material selected from the group consistingof 1 waxes, resins and mixtures thereof, as continuous phase,

thereby characterized that said colored droplets consist essentially ofa solution of a water-insoluble colorant which is at least one salt ofan organic base with an organic dyestuif sulfonic acid in a hydrophilicoxygen-containing organic liquid solvent for said salt which isimmiscible with said hydrophobic material.

References Cited in the file of this patent UNITED STATES PATENTS2,299,693 Green Oct. 20, 1942 2,299,694 Green Oct. 20, 1942 2,505,471Green Apr. 25, 1950 2,634,677 Klimkowski Apr. 14, 1953 2,800,457 GreenJuly 23, 1957 2,800,458 Green July 23, 1957 2,873,671 Florence Feb. 17,1959

9. A COATING COMPOSITION FOR THE PRODUCTION OF A DUPLICATING SHEETCONSISTING ESSENTIALLY OF A DISPERSION OF DISCRETE COLORED DROPLETS ASDISCONTINUOUS PHASE IN A PLASTIC NORMALLY SOLID HYDROPHOBIC MATERIALSELECTED FROM THE GROUP CONSISTING OF WAXES, RESINS AND MIXTURES THEREOFAS CONTINUOUS PHASE, THEREBY CHARACTERIZED THAT SAID COLORED DROPLETSCONSIST ESSENTIALLY OF A SOLUTION OF A WATER-INSOLUBLE COLORANT WHICH ISAT LEAST ONE SALT OFAN ORGANIC BASE WITH AN ORGANIC DYESTUFF SULFONICACID IN A HYDROPHILIC OXYGEN-CONTAINING ORGANIC LIQUID SOLVENT FOR SAIDSALT WHICH IS IMMISCIBLE WITH SAID HYDROPHOBIC MATERIAL.